Astronomers have, for the very first time, observed in real time a dying red supergiant star prior to, during, and after it exploded as a supernova, thus destroying itself and collapsing into either a neutron star or a black hole.
This discovery is unprecedented because previous observations of the star prior to its explosion were discovered post-supernova, when astronomers went back and found it in archival footage. In this case the astronomers were studying the star before it exploded, and thus got a far more detailed look at its behavior.
Prior to this, all red supergiants observed before exploding were relatively quiescent: they showed no evidence of violent eruptions or luminous emission, as was observed prior to SN 2020tlf. However, this novel detection of bright radiation coming from a red supergiant in the final year before exploding suggests that at least some of these stars must undergo significant changes in their internal structure that then results in the tumultuous ejection of gas moments before they collapse.
This data will require the computer modelers and theorists to completely revise their computer models and theories for explaining the ignition of a supernova.